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Potential of a 70 kDa IL ‐10‐like factor in synovial fluid from rheumatoid arthritis patients to augment superoxide generation by human neutrophils
Author(s) -
Nakamura Tadashi,
Yamamoto Tetsuro
Publication year - 2016
Publication title -
international journal of rheumatic diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 41
eISSN - 1756-185X
pISSN - 1756-1841
DOI - 10.1111/1756-185x.12166
Subject(s) - superoxide , synovial fluid , microbiology and biotechnology , biochemistry , medicine , cytochalasin b , arthritis , n formylmethionine leucyl phenylalanine , isoelectric point , chemistry , immunology , biology , enzyme , cell , pathology , osteoarthritis , alternative medicine
Aim To elucidate the role of polymorphonuclear leukocytes ( PMN s) in joint destruction during the inflammatory process in rheumatoid arthritis ( RA ) as related to superoxide generation. Methods Superoxide generation by human peripheral PMN s was measured by using a water‐soluble formazan dye, 2‐(4‐iodophenyl)‐3‐(4‐nitrophenyl)‐5‐(2, 4‐disulfophenyl)‐2H‐tetrazolium, monosodium salt, under PMN stimulation with N ‐formylmethionyl‐leucyl‐phenylalanine ( fMLP ) and cytochalasin B. Factors in synovial fluids ( SF ) from RA patients that may augment PMN superoxide generation were characterized via high‐performance liquid chromatography and isoelectric focusing. Results The formazan dye allowed measurement of superoxide generated in the xanthine‐xanthine oxidase system and by PMN s stimulated by cytochalasin B and fMLP in the presence of the intermediate electron transporter phenazine methosulfate. By using chromatography and electrophoresis, an RA ‐ SF protein with an apparent molecular size of 70 kDa and an isoelectric point of 8.3 was isolated and was demonstrated to increase superoxide generation by PMN s. The factor was heat‐labile and susceptible to protease treatment. This enhancing activity of the factor was absorbed by human PMN s and was somewhat immunoadsorbed with a specific monoclonal antibody against interleukin (IL)‐10. Conclusion The 70‐ kD a protein factor in RA ‐ SF increased superoxide generation by human PMN s, which suggests the possibility of its being related to IL ‐10. This factor may have a pathological role in RA joint destruction caused by PMN s and coinciding with rheumatoid inflammation, which suggests that PMN s, via superoxide generation, play an important role in RA joint destruction. IL ‐10 therefore likely has biological activity toward PMN s during synovial inflammatory chain reactions in RA.